During the Cold War, it wasn't hard to determine who could have been behind an airborne nuclear strike—just check behind the Iron Curtain. But in the modern era of nuclear proliferation, figuring out who set off a bomb would be more akin to crime scene investigation.

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Say a nuclear missile is launched somewhere in the world. To learn its origins, authorities would first need to collect airborne fallout samples from multiple altitudes. But doing so would also expose pilots to dangerous amounts of radiation. That's why Sandia National Labs has developed a way to make a drone do it—a new UAV-mounted radioactive fallout collection system can gather up the isotopes without a risk to any human pilots.

Dubbed the Harvester, this airborne particulate collection system is comprised of three nine-foot, 650-pound sampling pods, and some additional analysis hardware, mounted to the underside of an MQ-9 Reaper. Two pods do the active sampling, while the third hones in on the fallout's source by tracking the gamma radiation trail left behind. And while strapping these pods to the belly of a $36 million drone may seem an expensive option, it is still less expensive and more versatile than permanently modifying manned aircraft to carry it.

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It works by pushing air through each duct-like pod at 200 MPH (the Reaper's cruising speed). Radioactive material in that air gets stuck in a fine fiber mesh filter, and it's analyzed in real-time by the on-board radiation sensor. This sensor is quick, but not completely accurate. So once the UAV is back on the ground, researchers can remove the filter for further analysis. During a test run last September above Grand Forks Air Force Base, in Grand Forks, N.D., the Harvester system successfully collected and identified natural lead and bismuth isotopes generated from the decay of radon in the atmosphere.

"There's a high likelihood the Air Force will make Harvester operational in 2014 to augment its current manned aircraft collection capability," said Sandia project lead Joe Sanders, in a press release. "For maximum responsiveness, we continually engaged with the Air Force to address its technological and operational needs throughout the project."

Let's just hope no one drops a Little Boy before next year—or, well, ever again.